DNA exists in many possible conformations that include the A-DNA, B-DNA, and Z-DNA forms; of these, B-DNA is the most common form found in cells. The DNAs that do not fall into a right-handed Watson-Crick double-helix are known as non-B DNAs and comprise cruciform, triplex, slipped (hairpin) structures, tetraplex (G-quadruplex), left-handed Z-DNA, and others. Several recent publications have provided significant evidence that non-B DNA structures may play a role in DNA instability and mutagenesis, leading to both DNA rearrangements and increased mutational rates, which are hallmark of cancer.
The Advanced Biomedical Computing Center (ABCC) has systematically identified in several mammalian species the genomic regions predicted to form each non-B candidate structure and placed these into non-B DB. Currently, non-B DB provides the most complete list of alternative DNA structure predictions available, including Z-DNA motifs, quadruplex forming motifs, inverted repeats, mirror repeats and direct repeats and their associated subsets of cruciforms, triplex and slipped structures, respectively. The database also contains motifs predicted to form static DNA bends, short tandem repeats and homo(purine.pyrimidine) tracts. non-B DB also allows researchers to intersect non-B DNA information with positions of known variation in the genome to assess the possible disruption of these structures as a function of genotypic variation.
Please cite: Non-B DB v2.0: a database of predicted non-B DNA-forming motifs and its associated tools.
Regina Z. Cer, Duncan E. Donohue, Uma S. Mudunuri, Nuri A. Temiz, Michael A. Loss, Nathan J. Starner, Goran N. Halusa, Natalia Volfovsky, Ming Yi, Brian T. Luke, Albino Bacolla, Jack R. Collins and Robert M. Stephens.
Nucl. Acids Res. (2013) 41 (D1): D94-D100. doi: 10.1093/nar/gks955